<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .wechat{ float: left;}
        .wechat .wechat_code{display: none; height: 100px; width: 100px; background: red;}
        .wechat:hover .wechat_code{display: block;}
    </style>
</head>
<body>
<div class="wechat">
    <a class="wechat_account" href="#">我是微信号</a>
    <a class="wechat_code" href="login.html">我是二维码</a>
</div>
</body>
</html>